Why my GCs with Samsung memory does not reaches 100% max MemCtrl Load?

I just build my 1st mining rig.  Got it up and running for about 3 weeks now.

The rig has 6 GPUs running NiceHash QuickMiner DaggerHashimoto.

Four NVIDIA GeForce GTX 1660 MSi SUPER VENTUS XS OC with 6GB GDDR6 Hynix
* Memory Controller Load reaches max 100%
* Optimization profile:  Efficient

One NVIDIA GeForce GTX 1660 MSi SUPER VENTUS XS OC with 6GB GDDR6 Samsung
* Memory Controller Load reaches max 83%
* Optimization profile:  Efficient

One NVIDIA GeForce RTX 2070 MSi VENTUS 8G with 8GB GDDR6 Samsung
* Memory Controller Load reaches max 88%
* Optimization profile:  High